Compounds for obtaining polymeric flameproofing agents and the process for obtaining them, as well as the flameproofing agents thus obtained

ABSTRACT

New compounds are disclosed for obtaining novel polymeric flameproofing agents. The former are diphenols of the general formula:    &lt;IMAGE&gt;  (I)  where n=0 or 2. The latter are aromatic polyphenylphosphonates having recurring units of the general formula: &lt;IMAGE&gt; (II)  in which n equals 0 or 2, and are obtained by reacting (I) with phenylphosphonyl chloride. The latter are especially useful for the flameproofing of polyester and finished or shaped articles based on polyester.

This is a Division of application Ser. No. 790,997 filed Apr. 26, 1977and issued Sept. 26, 1978, as U.S. Pat. No. 4,117,042.

The present invention relates to new diphenols and to a process forobtaining them, as well as to the use of such compounds for obtainingpolyphenylphosphonates of dihydroxybenzoates which have an excellentflameproofing action on polyesters, and in particular on polymethyleneterephthalates.

It is already known from French Patent Application No. 2,081,803,published on the Dec. 10, 1971, to use as flameproofing agents forpolyesters, polyphenylphosphonates of aromatic diols, thepolyphenylphosphonates having recurring units of the formula: ##STR3##in which Y represents an alkylidene or a cycloalkylidene group havingfrom 1 to 6 carbon atoms, or a sulphonyl group. However, thoseflameproofing agents, which are derived from phenols, suffer from thedisadvantage of lowering the stability of the polyester to light and/orof possessing a mediocre stability to hydrolysis. Moreover, whenpolyesters which have been thus flameproofed are subjected to the AATCC34/69 test, they give very fluid droplets.

Linear polyesters are also known from French Patent application No.2,243,958, based on dicarboxylic acids and on diols, having from 3 to20%, expressed as mols, relative to the acid units of the polyester, ofrecurring units of the formula: ##STR4## in which R₁ is a hydrocarbonradical such as a phenyl radical and R is an alkylene, arylene oraralkylene group. Flameproof yarns are obtained by spinning thesepolymers.

In accordance with the present invention, new phenols have now beenfound which can be used very advantageously for the preparation of novelflameproofing agents, the phenols having the general formula: ##STR5##with n=0 or 2.

The present invention also relates to a process for obtaining these newphenols by esterifying parahydroxybenzoic acid with ethylene glycol, ata temperature of between about 150° C. and about 200° C., in therespective proportions of at least two mols of acid per 1 mol ofethylene glycol, and, if appropriate, subsequently brominating theproduct thus obtained according to any per se known process.

The present invention also relates to new aromaticpolyphenylphosphonates especially useful for the flameproofing ofpolyesters, the recurring units of which have the general formula:##STR6## in which n equals 0 or 2.

It also relates to a process for obtaining aromaticpolyphenylphosphonates of the general formula (II) by thepolycondensation of the phenols of the general formula (I) withphenylphosphonyl chloride, in proportions which are substantiallystiochiometric.

The phenols according to the present invention, of the general formula(I), may be prepared in various ways, for example in bulk or insolution. In the first case, the esterification of ethylene glycol withp-hydroxybenzoic acids takes place in the presence, or in the absence,of catalysts, which may be sulphuric acid, toluenesulphonic acid orphosphoric acid. The reaction takes place in the ratio of 1 mol of diolto at least 2 mols of parahydroxybenzoic acid. The temperature generallyvaries between 150° and 200° C.; above 200° C., degradation of theparahydroxybenzoic acid occurs; the reaction time generally variesbetween 1/2 hour and 5 hours, depending on the catalyst used, and thewater which is produced during the reaction is removed by distillation.Certain products, such as calcium acetate, may be added during thereaction to avoid etherification reactions.

The reaction can also take place in solution, for example innitrobenzene, and if desired, in the presence of catalysts such assulphuric acid or toluenesulphonic acid, the water produced again beingremoved by distillation.

The aromatic rings of the diphenol thus obtained may be brominated inthe proportion of two atoms of bromine per ring, according to any per seknown process, for example by a redox reaction (such as hydrobomic acidwith hydrogen peroxide or with potassium bromate).

The new brominated or unbrominated phenols are used for the preparationof new aromatic polyphenylphosphonates intended for the flameproofing ofpolyesters.

The diphenols thus obtained are polycondensed with phenylphosphonylchloride: they may be prepared by interfacial polycondensation, that isto say by dissolving each of the two components in immiscible solvents,or more simply by polycondensation in solution, in a suitable solventsuch as, for example, tetrachloroethane, and preferably in the presenceof a catalyst such as calcium chloride or magnesium chloride, at atemperature generally between 100° and 200° C., the starting reagentsgenerally being present in substantially stoichiometric proportions.

The polyphenylphosphonates according to this invention may be used withpolyesters such as polybutylene terephthalate andpoly(1,4-dimethylene-cyclohexylene terephthalate), and they areparticularly suitable for use with polyethylene terephthalate as well aswith copolymers containing up to about 80% of ethylene terephthalateunits, it being possible for the other units to be derived from otherdiacids, such as isophthalic acid, or other diols such as brominateddiols of the formula: ##STR7##

The said polyphenylphosphonates may be introduced into the bulk of themolten polyester, for example into an extruder, before extrusion in theform of yarns, films or monofilaments, in proportions which may varybetween 5 l and 20% by weight relative to the polymer, and preferablybetween about 8 and about 15%. They may also be applied at any timeduring the preparation of the yarns, films or monofilaments, as well asto the finished textile articles, which may be woven, knitted, and thelike, by impregnating the article with the flameproofing product in theform of a solution in an appropriate solvent, for example in methylenechloride.

The thus-treated articles retain a good heat stability, a goodresistance to hydrolysis, and a good stability to light.

The following examples, in which the parts and percentages are byweight, are given merely by way of illustration and without implying anylimitation on the invention.

In these examples, the flameproofing tests carried out are thefollowing:

the AATCC 34-69 test measuring the height destroyed and the number ofignited droplets;

measurement of the LOCC (Limiting Oxygen Concentration for Combustion)is effected according to the Standard Specification ASTM 2863-70 withrespect to plastic test-pieces, modified and adapted for textile samplesof size 5×16 cm, mounted on a rectangular frame;

the droplet test described in the French Journal Officiel of 26.7.1973,page 8,133, and modified by the Ministry of the Interior Decree whichappeared in the French Journal Officiel of 26.2.1976, page N.C. 1,013;and

the LCH inflammability meter test which is the subject of theexperimental specification AFNOR G 07-113, of July 1972.

EXAMPLE 1

A. Synthesis of glycol di-p-hydroxybenzoate in bulk

0.5 mol (69 g) of p-hydroxybenzoic acid, 0.2 mol (12.4 g) of ethyleneglycol, 0.69 g (1% relative to the p-hydroxybenzoic acid) oforthophosphoric acid, and 2 mg (50 ppm of Ca/glycol) of anhydrouscalcium acetate, are introduced into a reactor equipped with the usualmeans for heating and regulating.

Heating under nitrogen is carried out until complete melting occurs; thetotal duration of the reaction is 2 hours, the temperature varying from180° to 200° C., whilst the water formed is removed.

    ______________________________________                                        Reaction yield           67%                                                  Proportion of phenolic (OH) groups                                                                     90.5%                                                ______________________________________                                    

The product thus obtained (a mixture of monoester and of diester) ispurified by cold-washing with acetic acid.

The glycol di-p-hydroxybenzoate thus obtained has a purity of 98-99%.

B. Synthesis of glycol di-p-hydroxybenzoate in solution

5 mols (691 g) of p-hydroxybenzoic acid, 2 mols (124 g) of ethyleneglycol, 3.5 g of sulphuric acid, 20 mg (50 ppm of Ca) of anhydrouscalcium acetate, 800 ml of nitrobenzene and 300 ml of xylene, areintroduced into a reactor equipped with the usual means for heating andregulating.

Heating under nitrogen is carried out until distillation of the xyleneoccurs. The reaction is carried out for 6 hours, at a reactiontemperature of 132° to 175° C., with the removal of water.

After cooling, the crystalline product obtained is filtered off, washedwith xylene and, after treatment with animal charcoal, recrystallizedfrom an acetone/water mixture.

    ______________________________________                                        Yield                     50%                                                 Proportion of phenolic OH groups                                                                        98.5%                                               ______________________________________                                    

EXAMPLE 2 Preparation of brominated glycol di-p-hydroxybenzoate

33.40 g (0.2 mol) of potassium bromate are dissolved in 500 ml of water;30.20 g (0.1 mol) of glycol di(p-hydroxybenzoate), prepared as inExample 1, are added and 73.64 g (0.6 mol) of 66% strength hydrobromicacid are added little by little, with a temperature increase from 20° to40° C., over a period of 1 hour 30 minutes, the temperature beingmaintained at 40° C. for 2 hours.

The product obtained after filtering is washed with water, then with asolution of 5% strength sodium hyposulphite, and then again with water,and is recrystallized from an acetone/water mixture.

    ______________________________________                                        Yield                     56.80%                                              Bromine content           49.20%                                              Proportion of phenolic OH groups                                                                        99%                                                 ______________________________________                                    

EXAMPLE 3 Preparation of the polyphenylphosphonate of glycoldihydroxybenzoate

A reactor equipped with the usual means for heating and for regulatingis charged with: 97.3 g of 98% strength glycol di-p-hydroxybenzoate, 130cc of 1,1',2,2'-tetrachloroethane, anhydrous calcium chloride (750 ppmof calcium relative to the diphenol), and benzene (1 ml for 1 g ofdiphenol).

After removing the water as the water/benzene azeotrope and distillingoff the benzene, 62.7 g of 99% strength phenylphosphonyl chloride areintroduced dropwise, at a temperature of 130° C., and the whole isheated for 24 hours at the reflux temperature of the1,1',2,2'-tetrachloroethane. A quantity of tetrachloroethane, equal tothat introduced at the start, is added and the collodion is allowed tocool to ambient temperature. It is then poured dropwise, with agitation,into methanol: the polyphenylphosphonate precipitates and issubsequently filtered off, washed with methanol, dried and purified.

    ______________________________________                                        Specific viscosity measured in a 1%                                           strength solution at 25° C. in N-                                      methyl-pyrrolidone       0.34                                                 Quantity of phosphorus   7.3%                                                 Purity                  97.6%                                                 Stability to hydrolysis in aqueous                                            media:                                                                        pH  3 - 100° C. for 3 hours:                                                                   pH variation zero                                     pH 10 -  60° C. for 3 hours:                                                                   pH variation zero                                     ______________________________________                                    

EXAMPLE 4 Preparation of the polyphenylphosphonate of brominated glycoldihydroxybenzoate

The reaction is carried out in the same way as in Example 3, using asstarting compounds: 34.04 g of 99% strength brominated glycolparahydroxybenzoate, such as prepared according to Example 2, l insteadof glycol parahydroxybenzoate, 10.74 g of 99% strength phenylphosphonylchloride, CaCl₂ (750 ppm of Ca relative to the diphenol), 46 cm³ oftetrachloroethane and 30 cm³ of benzene.

The product thus obtained has the following characteristics:

    ______________________________________                                        Quantity of bromine (by weight)                                                                            40.69%                                           Quantity of phosphorus       4.17%                                            Purity                       99%                                              Specific viscosity (measured as                                               in Example 3)                0.20                                             Melting point (measured on the                                                DuPont 900ATD apparatus)     125° C.                                   Heat stability (DAM thermobalance                                             Ugine Eyraud type B 60):     loss                                              240° C. isotherm under nitrogen                                        for 2 hours                 3.1%                                              260° C. isotherm under nitrogen                                        for 2 hours                 6.3%                                             ______________________________________                                    

EXAMPLE 5

Three samples A, B and C are prepared from yarns made of polyethyleneglycol terephthalate, having respective weights of:

    ______________________________________                                        A:            128 g/m.sup.2 (knitted)                                         B:            450 g/m.sup.2 (woven)                                           C:            128 g/m.sup.2 (knitted)                                         ______________________________________                                    

Samples A and B are treated with a solution of the polyphenylphosphonateof glycol dihydroxybenzoate, prepared according to Example 3, inmethylene chloride, the samples being soaked, dried and treated on astenter at 200° C. Sample C is treated in the same way, but with thepolyphenylphosphonate of brominated glycol dihydroxybenzoate, such asprepared in Example 4. Each type of sample is treated with variouspercentages of flameproofing agents. The results are given in the tablebelow.

    ______________________________________                                                % of                                                                          flame-              Number                                                    proofing                                                                             AATCC test   of                                                          agent    Duration,                                                                              Height                                                                              ignited                                               deposited                                                                              seconds  cm    droplets                                                                             LOCC                                 ______________________________________                                        Sample A   0       200      26    >2     24                                              8       100      26     0     31.2                                           16        47      19    0-1    31.8                                           20       110      21     0     33                                   ______________________________________                                                % of                                                                          flame- LCH inflammability meter                                                 proofing                Surface                                               agent    Duration,                                                                              Height                                                                              area                                                  deposited                                                                              seconds  cm    cm.sup.2                                                                             LOCC                                 ______________________________________                                        Sample B  13       49       12    33     31                                             19       41       12    33     31                                   ______________________________________                                                % of                                                                          flame-              Number                                                    proofing                                                                             AATCC test   of                                                          agent    Duration,                                                                              Height                                                                              ignited                                               deposited                                                                              seconds  cm    droplets                                    ______________________________________                                        Sample C   8.6     130      26    0                                                     11       95       21    0                                                     15       83       20    0                                           ______________________________________                                    

EXAMPLE 6

A knitted fabric (80 g/m²) based on a copolyester derived frompolyethylene glycol terephthalate and a brominated diol of the formula:##STR8## in a quantity such that the copolyester contains 5.3% ofbromine, is prepared.

The knitted fabric is treated, by the method described in Example 5,with the flameproofing agent prepared according to Example 3.

    ______________________________________                                        % of                                                                          Flame-                                                                        proofing AATCC test       Number                                                                        of                                                  agent    Duration,  Height,   ignited Droplet                                 deposited                                                                              seconds    cm        droplets                                                                              test                                    ______________________________________                                        0        80         26        5       >2                                      9        5          11        0        0                                      20       5           8        0        0                                      ______________________________________                                    

What is claimed is:
 1. A phenol having the formula: ##STR9## 2.Polyester flameproofed by admixture with an aromaticpolyphenylphosphonate consisting of recurring units of the formula:##STR10## in which n equals 0 or
 2. 3. A finished article based onpolyester flameproofed by means of an aromatic polyphenylphosphonate asdefined in claim 2.